This invention relates to a fluorescent display device having grid electrodes or control electrodes arranged on substantially the same plane as a display section and a method for manufacturing the same, and more particularly to a fluorescent display device including control electrodes of which electric field control is facilitated and a method for manufacturing the fluorescent display device at a low manufacturing cost and with high productive efficiency.
In general, a fluorescent display device, as shown in FIG. 8, includes a fluorescent substrate structure 19 comprising a substrate 8 made of an insulating and heat-resistant material such as a glass plate or the like and a display section 10 arranged on the substrate 8, a light-permeable front cover 13 made of a glass plate or the like and arranged opposite to the fluorescent substrate structure 19, and side plates 14 forming a side portion of the display device, which are hermetically assembled together through a sealing material such as low-melting frit glass or the like to from a vacuum casing 15. The display section 10 includes anodes 7 and phosphor layers 6 deposited thereon and is arranged in the vacuum casing 15 together with cathodes 11 for emitting electrons and grid electrodes 12 formed with apertures in a mesh-like manner. The vacuum casing 15 is also provided therein with wirings 17 in a manner to be arranged below insulating films 18 and electrically connected to the display section 10. To the wirings 17 are connected lead wires 16 which are outward led out through the vacuum casing 15. In the fluorescent display device thus constructed, the grid or control electrodes 12 and anodes 7 function to select and control electrons emitted from the cathodes 11 so as to impinge them on the phosphor layers 6, resulting in desired luminous display being carried out.
As will be noted from the above, in the conventional fluorescent display device, the grid electrodes 12 are arranged above the phosphor layers 6 in a manner to be spaced therefrom, therefore, it is very hard to keep a distance between each of the grid electrodes 12 and each of the phosphors 6 constant, resulting in non-uniformity in luminance.
In manufacturing of the fluorescent display device, the grid electrodes 12 are made by subjecting metal sheets of stainless steel or the like to etching at least one by one at each time. Also, each of the grid electrodes 12 is required to be formed into a configuration which permits them to be arranged between the cathode 11 and the anode 7. Further, formation of the grid electrode 12 into a large size causes it to be deflected at a central portion thereof due to its weight, so that it is hard to keep a gap between the phosphor layer 6 and the anode 7 constant. Thus, the conventional method leads to deterioration of productivity and an increase in manufacturing cost.